Free wheel with self-centering cage

ABSTRACT

Free wheel, the cage (5) of which consists of two identical half cages (6, 7) each incorporating an intermediate cylindrical envelope (8) which is firmly fixed to portions forming surfaces (9, 10), which may or may not be continuous, for bearing against the surfaces of the shaft (1) and the bore (2), or the same side as, or on the side remote from the row of cams (3), the said intermediate envelope (8) incorporating notches (12 to 18) of such a shape that it allows the two half cages when positioned facing one another to be fitted together by an axial movement, enclosing the said spring between the central envelope (8) and the surface (9) for bearing upon the shaft, and leaving rectangular openings (15-17, 16, 15-17, 16) for cams (3) to be radially introduced, which thus lock axially the two half cages.

The invention concerns free wheels of the type with cams which become jammed, intended to be mounted in devices in which the transmission of torque between the inner component and the outer component, or vice versa, but also the centering of the said components relative to one another and the transmission of radial forces from one to the other can take place through the intermediary of the said free wheels.

For greater clarity of the following description, the inner component with an external cylindrical bearing surface will be referred to as a shaft, irrespective of whether it concerns a true solid shaft, a hollow shaft or a ring, and the outer component with a cylindrical bore will be referred to as a bore, irrespective of whether it concerns a plain bore in a fixed or movable component or an intermediate ring. The external surface of the shaft and the internal surface of the bore thus form the two bearing surfaces between which the cams become jammed. In the application being considered, it is also between these surfaces that centering must take place, that is to say the transmission of radial forces.

As principal applications, reactors of hydrokinetic torque convertors and epicyclic trains of automatic gearboxes may be mentioned, in which the free wheels must be capable of providing simultaneously two separate functions, namely a function as a pure free wheel carrying out the transmission of a unidirectional torque between the shaft and the bore, or vice versa, and a function as a bearing carrying out relative centering of the two components in rotation and supporting a modest radial load regulated particularly during periods of rotation as a free wheel.

Excluding of course conventional solutions in which the two functions, free wheel and bearing, are provided by separate components, a number of embodiments of free wheels are known which are said to be self-centering, incorporating centering components in which the bearing surfaces of the bore come to bear against the shaft so as to provide the transmission of radial forces with sliding on one or the other of the components.

U.S. Pat. No. 2,912,086 thus describes the free wheel device in which the centering function is provided by two attached centering flanges, with a U-shaped cross-section, situated so as to be coaxial with the free wheel on each side of the latter. Such an arrangement has a number of disadvantages, in particular the multiplicity of components together with difficulty of mounting and of handling.

French Pat. No. FR-2,340,476 describes another device in which the function of centering is provided by a succession of cage portions interposed between the shaft and the bore, each portion being provided with a cam and an individual spring. Again the device has a multiplicity of components together with numerous difficulties of mounting and of handling the separate components.

French Pat. No. FR-2,486,606, in the name of the applicant company, describes an improved free wheel device with cams in which the centering function is provided by a one-piece cage with a U-shaped transverse section open axially, the said cage also enclosing the cams and the return spring. In its simplest version, this cage has the disadvantage of providing a relatively modest radial load capacity by reason of the flexibility of the U-shaped section on the side of the opening. In its most sophisticated version, this disadvantage is overcome to a certain degree by means of reinforcing fingers, but at the cost of greater complexity and greater mounting difficulty.

The aim of the invention is to overcome the foregoing disadvantages by constructing a self-centering free wheel which is at the same time compact, inexpensive, and easy to assemble and to handle.

The invention consists, in a free wheel of the type being considered incorporating cams for jamming and a single strip spring situated in a cage, of constructing this cage with the aid of two identical half cages lying between the diameter of the shaft and the diameter of the bore, each incorporating an intermediate cylindrical envelope of a diameter intermediate between the two aforementioned diameters, firmly fixed to portions forming surfaces, which may or may not be continuous, for bearing against the surfaces of the shaft and of the bore, on the same side or on the side remote from the row of cams, the said envelope incorporating notches of such a shape that it allows the two half cages when positioned facing one another to be fitted together by axial movement, enclosing the said spring between the central envelope and the surface or surfaces for bearing against the shaft, and leaving rectangular openings for the cams to be radially introduced and held by the spring, the axial locking in this position of the two half cages relative to one another being provided essentially by the presence of the cams, the lateral surfaces of which bear against two opposite sides of the said notches.

Other features of the invention would emerge from the following description of an embodiment given by way of example and shown in the accompanying drawing, in which:

FIG. 1 is a partial section of a first version, the section plane being perpendicular to the axis;

FIG. 2 is a section through II--II shown in FIG. 1;

FIG. 3 is a diagrammatic illustration developed in perspective of two portions of the two half cages positioned face to face, for this same version;

FIG. 4 corresponds to FIG. 3 after axial approach and fitting together and before the introduction of the cams, the spring not being shown; and lastly

FIGS. 5 and 6 are similar illustrations to those shown in FIG. 3, for second and third versions, respectively.

FIG. 1 shows the external surface 1 of the shaft and the internal surface 2 of the bore, surfaces between which the cams 3 are situated, together with their single spring in the form of a strip 4.

In accordance with the invention, the cage 5 which holds together the spring 4 and the cams 3 consists of two identical half cages 6 and 7 positioned face to face.

Each of these half cages incorporates an intermediate cylindrical envelope 8 of a diameter between that of the shaft 1 and that of the bore 2, as shown in the figures. In the developed illustrations of FIGS. 3 to 6, these cylindrical surfaces are shown flat for greater clarity.

For each of the half cages, the intermediate envelope 8 is firmly fixed to two cylindrical bearing surfaces 9 and 10 intended to bear against the surfaces 1 and 2, respectively, through the intermediary of a continuous flange 11 in the first version shown in FIGS. 1 to 4.

In addition, in accordance with the invention, each of the intermediate envelopes 8 incorporates a definite number of notches which are evenly spaced and are equal in number to the number of cams. Each of these notches consists respectively of an edge 12, situated for example along a generating line, an edge 13 which corresponds in the first version to the base of the return carrying each of the surfaces 10, an edge 14 which is parallel to and faces the edge 12, an edge 15 which is perpendicular to the axis, an edge 16 which is parallel to and faces the edge 12, an edge 17 which is parallel to and faces the edge 15 and an edge 18 which is situated in the extension of 14, for example, each line 14-18 also being essentially in the middle of the gap between two successive edges 12, and the edges 14 and 18 being essentially of equal length.

Each half cage is preferably made by stamping from metal strip having a low coefficient of friction, but may also be made of plastic by injection moulding.

In this way, after having formed two identical half cages 6 and 7 and having positioned them face to face after reversing one of them as shown in FIG. 3, their mutual fitting together may be achieved by moving axially towards one another so as to arrive at the condition shown in FIG. 4. In fact, each remaining solid portion of an intermediate cylindrical envelope 8 is a projection which enters a notch in the other cylindrical envelope 8 so as to form a complete cylindrical envelope but leaving, as shown in FIG. 4, rectangular openings formed by the assembly of the edges 15, 16 and 17 of the two half cages. As shown in FIG. 4, each of the rectangular openings has edges which are formed on both of the half cages.

To improve the centering of the two half cages relative to one another, the edge 19 of each remaining portion of the envelope 8 between two notches may incorporate advantageously a projection 20 forming a centering peg, entering into an opening 21 formed in the continuous flange 11, in the region of the imaginary edge 13, in the base of the return carrying each bearing surface 10.

The spring 4 is of course placed in position between the two half cages 6 and 7 before moving them together, this spring not being shown, however, in FIG. 3 and the figures which follow for greater clarity. In addition, once the fitting together is achieved by moving towards one another, the cams 3 are introduced radially into the rectangular openings previously defined in which they are cogged and are radially held by the spring. In addition, the presence of these cams in these openings provides in turn the axial locking of the two half cages relative to one another owing to the edges 15 and 17, respectively, which bear against the lateral surfaces of the cams 3. The cams comprise means for axially locking the half cages together. Manufacture is thus extremely easy as it requires a single type of cage component which are only needed to be used in pairs, and it is only necessary to bring them together with the interposition of the spring and they are automatically locked as soon as the cams are introduced, without having to provide either any fixing component, or any additional operation. Moreover, the whole unit remains capable of being dismantled if the need should arise.

In the first version which is described above, the surfaces 9 of each half cage are continuous, while the surfaces 10 are interrupted.

The second version, shown in FIG. 5, differs from the preceding version only in that the continuous flange 11 of each half cage is replaced by an interrupted flange formed by portions 11a and 11b which are folded back alternately towards the inside and the outside of the intermediate envelope 8. In this case, the edge 13 actually exists as an edge of the notch, and centering by the pegs 20 and the openings 21 is no longer possible. In addition, if the external bearing surfaces 10 continue to be interrupted, the internal bearing surfaces 9 are in their turn interrupted. Apart from these differences, all that which is stated above in relation to manufacture and mounting remains valid.

Lastly, in the version shown in FIG. 6, the surfaces 9 are once again continuous, and the surfaces 10 are interrupted, but in this case, the surfaces 10 are firmly fixed to the intermediate envelope 8 of the corresponding cage, no longer by the continuous flange 11, but by a second interrupted flange 11c situated on the opposite side and joined to the wall 8 by an intermediate portion 8a, the internal cylindrical surface of which is essentially at the diameter of the external cylindrical surface of the envelope 8, in such a way as to straddle the edge 13 of the opposite half cage. Again in this case, the centering pegs 20 cannot be used but are advantageously replaced by fitting together the portions 8a of one half cage onto the portions 8 of the other half cage. 

I claim:
 1. A self-centering free wheel of the type incorporating a plurality of cams (3) for jamming abutment between the inner surface of a bore (2) and the outer surface of a shaft (1) disposed within said bore, and comprisinga cage (5) comprising two identical half cages (6,7) disposed between said shaft and said bore surface, and supporting said cams therein, a spring (4) within said cage for simultaneously providing a tilting torque to said cam while radially retaining said cams within said cage, each of said half cages having bearing surfaces (9) on one side thereof for bearing against the surface of the shaft (1) and havign bearing surfaces (10) on the other side thereof for bearing against the surface of said bore (2) and to transmit a radial force from one surface to the other surface, each of said half cages including an intermediate cylindrical envelope (8) having a diameter which is intermediate the diameter of said shaft and of said bore, said intermediate cylindrical envelope (8) on eah of said half cages having notches, said notches being arranged to form a plurality of rectangular openings in said cylindrical envelope when said half cages are fitted together by axial movement to form said cage (5), each of said rectangular openings having edges which are located on both of said half cages, said spring (4) disposed between said cylindrical envelope (8) and bearing surface 9 of said cage, each of said cams supported in one of said rectangular openings in said cylindrical envelope when said half cages are fitted together, said spring engaging and retaining said cams within said cage, said cams within said rectangular openings comprising means for axially locking said half cages together.
 2. The self-centering free wheel as defined in claim 1 wherein said bearing surface (9) on one side of each of said half cages for bearing against the surface of said shaft (1) is continuous and is connected to said intermediate envelope (8) and to said bearing surfaces 10 by a flange (11), said bearing surfaces (10) for bearing against the surface of said bore (2) being discontinuous.
 3. The self-centering free wheel as defined in claim 2 wherein each intermediate cylindrical envelope (8) has a centering peg (2) projecting from one edge of said envelope and engaging a corresponding slot (21) provided in said flange (11) when said half cages (6,7) are axially joined to form said cage (5).
 4. The self-centering free wheel as defined in claim 1 wherein said bearing surfaces (9,10) on opposite sides of said half cages (6,7) are discontinuous, sid bearing surfaces (9,10) being secured to said intermediate cylindrical envelope by a series of flanges (11a,11b) alternately projecting toward the surface ofthe shaft 1 and the surface of the bore
 2. 5. The self-centering free wheel as defined in claim 1 wherein said bearing surface (9) on each half case (6,7) for bearing against the surface of said shaft (1) is continuous and is secured to said intermediate cylindrical envelope (8) by a continuous flange (11), and said bearing surface (10) on each half cage (6,7) for bearing against the surface of said bore (2) is interrupted to form a plurality of separate bearing surfaces (10), each of said separate bearing surfaces (10) secured to said intermediate envelope (8) by flanges (11c).
 6. The self centering from wheel as defined in claims 1,2,3,4, or 5 wherein each half cage is made by stamping from a metal ribbon having a low coefficient of friction.
 7. The self-centering free wheel as defined in claims 1,2,3,4, or 5 wherein each half cage is made of plastic by injection molding. 